It's a mass delusion of a sort, and unlike an economic bubble we do not even have the benefit of historical data to suggest a bubble.
Tobold put it another way.
What I observe more and more, is a culture in which the dedication you show towards a single game and character gives you status in the eyes of other players. Everything players in MMORPGs are so proud about is stuff they acquired because they spent more time and effort on achieving it. Thus they concentrate on a single game and a single character and advance him as much as possible.
It's a fashion trend. Someday we may look back and wonder why we cared so much and our children will laugh at screenshots, just as we laughed at our own parents for wearing bell-bottoms. Or in some cases, you were the parent, so I'm going to throw in an extra laugh for you (lol).
Few people like questioning good times. We get mad at and ignore the doomsayers before the bubble bursts, and then after we ask why they didn't warn us. There is something to it: economics is based so much on confidence and moods that a bubble can seem normal, though we don't like to say the same about a burst. But still, there is an underlying reality to the economy and markets, which eventually, always reasserts itself. Maybe we can say there isn't such a thing for WoW. It's all just $15 a month and there is no price bubble. Oh no? Oh yes. Race changes, ponies, pets, perhaps even server transfers. There is a bubble and we're all pouring in money, what happens when we stop thinking its worth anything?